54=x^2-14x+49

Solution for 54=x^2-14x+49 equation:

54=x^2-14x+49

We move all terms to the left:

54-(x^2-14x+49)=0

We get rid of parentheses

-x^2+14x-49+54=0

We add all the numbers together, and all the variables

-1x^2+14x+5=0

a = -1; b = 14; c = +5;
Δ = b2-4ac
Δ = 142-4·(-1)·5
Δ = 216
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{216}=\sqrt{36*6}=\sqrt{36}*\sqrt{6}=6\sqrt{6}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(14)-6\sqrt{6}}{2*-1}=\frac{-14-6\sqrt{6}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(14)+6\sqrt{6}}{2*-1}=\frac{-14+6\sqrt{6}}{-2}
$